package com.eatme.core.map;

import java.util.ArrayList;
import java.util.Random;

public class BSTMap<K extends Comparable<K>,V> implements Map<K,V> {

    private class Node {

        private K key;

        private V value;
        private Node left,right;

        public Node(K key,V value) {
            this.key = key;
            this.value = value;
            left = null;
            right = null;
        }

    }

    private Node root;

    private int size;

    public BSTMap() {
        root = null;
        size =0;
    }

    // 向二分搜索树中添加新的元素(key,value)
    @Override
    public void add(K key, V value) {
        root = add(root,key,value);
    }

    // 向以node为根的二分搜索树插入元素(key,value), 递归算法实现
    // 返回插入新节点后二分搜索树的根
    private Node add(Node node, K key,V value) {
        if (node == null) {
            size++;
            return new Node(key,value);
        }
        else if (key.compareTo(node.key)<0) {
            node.left = add(node.left,key,value);
        }
        else if (key.compareTo(node.key)>0)
            node.right = add(node.right,key,value);
        else // key.compareTo(node.key) == 0
            node.value = value;

        return node;
    }


    // 从二分搜索树中删除元素键为key的节点
    public V remove(K key) {
        Node node = getNode(root,key);
        if (node != null) {
            root = remove(root,key);
            return node.value;
        }
        return null;
    }

    @Override
    public boolean contains(K key) {
        return getNode(root,key)!=null;
    }

    @Override
    public V get(K key) {
        Node node = getNode(root,key);
        return node == null ? null : node.value;
    }

    @Override
    public void set(K key, V newValue) {
        Node node = getNode(root,key);
        if (node == null)
            throw new IllegalArgumentException(key +"doesn't exist.");
        node.value = newValue;
    }

    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size==0;
    }

    // 返回以node为根节点的二分搜索树中, key所在的节点
    private Node getNode(Node node,K key) {
        if (node == null)
            return null;
        if (key.compareTo(node.key)==0)
            return  node;
        else if (key.compareTo(node.key)<0)
            return getNode(node.left,key);
        else // key.compareTo(node.key)> 0
            return getNode(node.right,key);
    }

    // 返回以node为根的二分搜索树的最小值所在的节点
    private Node minimum(Node node) {
        if (node.left==null)
            return node;
        return minimum(node.left);
    }

    // 删除掉以node为根节点的二分搜索树中最小节点
    // 返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node) {
        if (node.left==null) {
            Node rightNode = node.right;
            node.right = null;
            size--;
            return rightNode;
        }
        node.left = removeMin(node.left);
        return node;
    }

    // 删除以node为根的二分搜素树中键为key的节点,递归算法
    // 返回删除节点后新的二分搜索树的根
    private Node remove(Node node, K key) {
        if (node == null)
            return null;
        if (key.compareTo(node.key)<0) {
            node.left = remove(node.left,key);
            return node;
        }else if(key.compareTo(node.key)>0) {
            node.right =remove(node.right,key);
            return node;
        }else { // key.compareTo(node.key) == 0
            // 待删除节点左子树为空的情况
            if (node.left==null) {
                Node rightNode = node.right;
                node.right = null;
                size--;
                return rightNode;
            }
            // 待删除节点右子树为空的情况
            if (node.right==null) {
                Node leftNode = node.left;
                node.left = null;
                size--;
                return leftNode;
            }

            // 待删除节点左右子树均不为空的情况
            // 找到比待删除节点大的最小节点,即待删除节点右子树的最小节点
            // 用这个节点顶替待删除节点的位置
            Node successor = minimum(node.right);
            successor.right = removeMin(node.right);
            // size++;
            successor.left = node.left;

            node.left =node.right = null;
            // size--;
            return successor;
        }
    }

    public static void main(String[] args) {
        ArrayList<Integer> arrayList = new ArrayList<>();
        Random random = new Random();
        for (int i = 0; i < 100; i++) {
            arrayList.add(random.nextInt(100));
        }
        System.out.println(arrayList);
        System.out.println("arraylist size:"+arrayList.size());
        BSTMap<Integer,Integer> map = new BSTMap<>();
        for (int i = 0; i < arrayList.size(); i++) {
            if (map.contains(arrayList.get(i)))
                map.set(arrayList.get(i),map.get(arrayList.get(i))+1);
            else
                map.add(arrayList.get(i),1);

        }

        System.out.println("Total different numbers: " +map.getSize());

        System.out.println("Frequency of 0: " +map.get(0));
        System.out.println("Frequency of 1: " +map.get(1));
    }
}
